This invention relates to a control mechanism particularly applicable for use in a temperature control system in a motor vehicle wherein the control mechanism selectively interconnects various vacuum and/or electrically operated accessories with a vacuum source or an electrical source.
A typical temperature control system for a passenger vehicle serves to control flow and condition of air inside the vehicle by manual linear displacement of two actuators available to the vehicle operator. One of the actuators is a vacuum valve-electrical circuit actuator and the other is a heater temperature control actuator. Displacement of the heater temperature control actuator controls the temperature of the air blown into the vehicle.
The vacuum valve-electrical circuit actuator travels back and forth on the dashboard through several detent positions. This provides selective connection between a vacuum source port and one or more valve ports. It also provides selective connection between the vehicle battery and one or more electrical circuits. The valve ports are connected to individual vacuum motors which operate various vanes to open and close air ducts. The electrical circuits are connected to various electrical control devices, such as an electrically operable air conditioning clutch and the like.
Such control mechanisms include a valve body which typically has a flat surface with a plurality of ports, each communicating with various vacuum inlets and outlets. A valve plate faces the flat surface and has a plurality of chambers defined therein by peripheral walls which extend toward and abut the flat surface. One of the ports serves as a vacuum port and is connected to a vacuum source and the other ports connect to various vacuum motors to operate various vanes and the like. When the valve plate is displaced relative to the valve body, the vacuum port is selectively connected to one or more of the other ports to provide the desired control of air flow and condition.
The U.S. Pat. Nos. to A. Kenny et al. 3,856,045 and T. Fiddler et al. 3,637,962 disclose control mechanisms similar to that as described above wherein a rotor drives a valve plate relative to a valve body to provide the selective interconnections of the ports while at the same time actuating electrical switches to complete electrical circuits. Both Kenny and Fiddler propose that the rotor be provided with camming mechanisms which rotate with the rotor and in so doing cam against and actuate various switches located around the periphery of the rotor to cause various electrical circuits to be opened or completed. Neither Kenny nor Fiddler suggest that the rotor drive both a valve plate for interconnecting valve ports as well as an electrical switch plate for interconnecting various electrical leads, as opposed to the peripheral switch actuating camming mechanisms employed.
Each actuator of such control mechanisms in a motor vehicle typically includes a lever arm that protrudes through a slot on a face plate mounted on the vehicle's dashboard. A control knob is mounted on the end of the lever arm. The control knob may be manually displaced along a linear path through selected detent positions. The vacuum valve-electrical switch actuator may have detent positions such as OFF, MAX and NORM (for maximum and normal air conditioning operations). Additional positions may be VENT, FLOOR and DEF (for defrost). It is important that the control knob of such an actuator move along a linear path parallel to the face plate on the dashboard, as opposed to an arcuate path, for passenger safety reasons. This linear movement of the control knob affects the design of the actuator lever arm. For example, the U.S. Pat. No. to A. F. Raab 3,721,779 employs an actuator arm having a control linkage wherein the lever arm is rotatable and slidable about a pivot post so that as the operator displaces the control knob along a linear path in front of the face plate on the dashboard, the actuator arm pivots about and slides relative to the pivot post. The actuator lever arm is, in turn, in engagement through a linkage mechanism with a slidable carriage which is displaced to various positions at which electrical circuits are completed.
There is, however, no teaching in the Raab patent of an actuator lever arm mechanism which serves as a linear-to-rotary converter. Moreover, Raab does not suggest telescoping movement of a tongue into and out of a channel located on the rotor arm so that as the control knob is linearly displaced, the tongue slides into and out of the channel while driving the rotor arm in an angular manner about its axis of rotation. The use of such a structure will permit the tongue to be a totally separate element to be coupled to the rotor arm only when the control mechanism is in place behind the face plate on the dashboard. Also, the tongue of such an arrangement may be assembled to the face plate rather than the rotor structure.